Based upon above discussion, we can evaluate the transferability of pre-trained models by measuring the feature diversity and separation via metrics of evaluating \(\mathcal {NC}\)  [1]}, [2]}, which defined as follows
\(\mathcal {NC}_1\;:=\;\frac{1}{K}\operatorname{trace}\left(\Sigma _ W\Sigma _B^\dagger \right).\) 
